Re: *newbie* output of ScalarTripleProduct

*To*: mathgroup at smc.vnet.net*Subject*: [mg106772] Re: *newbie* output of ScalarTripleProduct*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Sat, 23 Jan 2010 07:32:08 -0500 (EST)

On 1/22/10 at 5:41 AM, marco.fax at email.it (pippo) wrote: >I'm (almost) new to mathematica ... I coped this from some tutorial >Needs["VectorAnalysis`"] >r1 = {1, -3, 2} >r2 = {3, 7,-5} >r3 = {4, 1, 6} >r={x,y,z} >ScalarTripleProduct[r-r1,r2-r2,r3-r1]==0 >the output i get is: Out[6]= True >What am I missing ? What where you expecting? The middle argument given to ScalarTripleProduct is r2-r2 which is clearly {0,0,0}. If any one of the three vectors is {0,0,0} the triple scalar produce will be zero. So, Mathematica has correctly reported the computed triple scalar product equals 0.